AHC: Reverse secession

Your challenge is to have the American Civil War happen start with the secession of the North rather than the south. The war diesnt necessarily have to start in the 1860s, but late PoDs are preferred. So how can it be done?
 
Generally, you need to make the north believe that they can't stay in the Union any longer on the terms of the south.

The obvious is to change on or more of the following:

1-Kansas-Nebraska Act (Perhaps legislating that there will be automatically slavery there, or somehow make it easier for southerners to populate the area so that they become slavery territories. That could lead to Bloody Kansas equivalent become a PR victory for the south.)

2-Dred Scott (but could it be more outrageous for the north than OTL?)

3-Presidential election of 1860, or previous, or next. I have no idea how Lincoln cannot be elected, though.

For 1, you need to change the 3/5 compromise to allow the act to pass in another form. The butterflies will negate this scenario, though.
 
To not get Lincoln elected, you need to split the northern vote instead of the southern. Let's say the Democrats find a compromise candidate, while Lincoln is faced with a abolitionist third party and a smaller fourth party which is more moderate than Lincoln. Maybe it could squeak out a Democratic victory, and thus perhaps lead to a nullification crisis over the Fugitive Slave Act, followed by succession.
 
Let's say the Democrats find a compromise candidate,
The problem is finding a compromise candidate.

You would probably have to have the POD earlier, maybe a different candidate in one of the earlier presidential elections. Maybe Lewis Cass wins instead of Taylor (dunno how plausible that could be) and given his popular sovereignty stance, he might inflame things.
 
(Probably a stupid) Question/comment: it seems to me that the South would be quite a bit less likely to actually want to force the North to return to the United States after a hypothetical northern secession. So would the South even necessarily fight a Civil War with the North? What can be done to make the South more likely to do so? Or is that totally irrelevant, the focus being on getting northern secession, and it's just assumed that a Civil War would be the case?
 
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